Scientists in Japan have taught a human-sized robot to imitate the steps of a dancer. They say the prancing "dancebot" could be used to record the movements of traditional dances that are being lost as their performers die off.

To demonstrate the robot's prowess the team programmed the 1.5 metre tall machine to imitate the graceful sways and whirls of the aizu bandaisan, a Japanese folk routine. To prove its accuracy, the robot can perform alongside a human dancer. And despite its Terminator appearance, the robot is remarkably lifelike.

Shin'ichiro Nakaoka and his colleagues at Tokyo University taught the dancebot - named HRP-2 or Promet - using video capture techniques to record human dance movements. According to New Scientist magazine these were converted into a sequence of robotic limb movements and fed into Promet's processors.

"They have got it to directly copy human movements. That is very difficult because the joints of the robot are very different from the joints of a human," said Noel Sharkey, a robotics expert at Sheffield University. The advance would allow robots to perform human-like movements on factory production lines.

Although its rendition of the mainly upper-body aizu bandaisan dance is impressive, the robot - produced by Kawada Industries - has difficulty with complicated leg movements. Any step more demanding than lifting a foot is likely to result in the 58kg automaton losing its balance and falling over. The team published its results in the International Journal of Robotics Research.

Despite Promet's lifelike appearance and fluid movements there is a long way to go to a truly intelligent robot butler or soldier. "It is not a thinking intelligent robot. What you have got is a set of processes that translate human movement into joint movements for a robot. That is it," said Prof Sharkey. "It is not going to start copying people doing other things or doing anything really advanced."

Even simple tasks like making a cup of tea in an unfamiliar kitchen are a major challenge because recognising objects in new environments is difficult.

Military powers are becoming increasingly interested in the possibilities that robots present.

Last year the South Korean military unveiled a robot border guard built by Samsung that can shoot targets up to 500 metres away, and could be programmed with a shoot-to-kill policy.

The US is developing a remote-controlled stretcher bearer called the Battlefield Extraction-Assist Robot (Bear) to help evacuate casualties. It is also nearing its goal of replacing one third of its ground vehicles with autonomous robots .

As robots become more integrated into the military, it will make it easier for governments to go to war, said Prof Sharkey, because they will have to worry less about the negative public reaction to media images of body bags coming home.

The Bear robot may look cute and save soldiers but it is all part of robots taking over the battlefield, Prof Sharkey said. "The fact it is made to look like a bear deflects your attention from what it really is. I don't see it as entirely benign. It's still developing a military technology, so ultimately it is a fighting machine."

As for the dancebot, if it can be tweaked to handle more leggy British folk dances it may be popular with purists who want to see traditional dances preserved.

"You've got two schools of thought, one which says let's preserve them in aspic and have them there forever and another which says things never stay like that," said Peta Webb, assistant librarian at the English Folk Dance and Song Society in London.

She prefers to see dances change and evolve: "It is like language. If you think about the development of language we are constantly developing new slang and dropping old slang."

Others will need more convincing. "My impression is that there would still be a human element lacking. The robot would still look, for the want of a better word, robotic," English folk dancer Joe Healey told New Scientist magazine.

Review: Pas de machine

The dance-world has always been fascinated with automatons. Coppélia, first performed in 1870, is about a man who falls in love with a life-sized doll. In Wayne McGregor's Nemesis (2002), dancers wore arm-extensions modelled on the limbs of the praying mantis, and this autumn, on London's South Bank, the French company Beau Geste is performing Transports Exceptionnels, a tender love-duet for a man and a mechanical digger.

So the interface between humans and machines is nothing new, and it's tempting to imagine a whole corps de ballet of robots performing Swan Lake, but it's unlikely machines will replace human performers altogether, since the focus of the theatre arts is the relationship between the audience and the fallible human performer.

Dominique Boivin, choreographer of Transports Exceptionnels, speaks of the desire "to give body and life to something purely mechanical - the machine", and perhaps this is the mirror-reflection of the desire of dance-makers like McGregor to take human movement into the mechanical. What's certain is that the meeting point of the two will continue to fascinate. As things stand, the dancebot would fail even the simplest audition. The damn thing can't jump!Luke Jennings